Model railroading is a life-long hobby for those that choose to make it so. I would argue that, compared to other hobbies, model railroading offers enjoyment at various levels, which is one angle that makes this hobby so great. When you are a beginner, just starting out, the hobby is entertaining. As you grow in the hobby, your skills and vision become more refined, and you can take it as far as you want to take it.
One example of that is my 3279. This is a classic engine that I purchased in 1989, manufactured by Athearn Inc. in Compton, California. This was part of their regular lineup and was painted at the factory in the Conrail livery. Even at that time, I was interested in detailing locomotives and so I added several parts to the model to more closely represent the 'real' Conrail 3279, formerly a Reading Company GP40-2. This meant that I needed to change the size of the fuel tank, add a cab-signal control box, snowplow, lift bars, and MU hoses, paint & decal the number boards and handrails, and weather the engine.
As my skills improved over the years, the 3279 started to look shabby in comparison to models I had finished more recently. Other parts became available. My research showed me ways in which I could further improve the model. And finally, the conversion to DCC several years ago presented a great opportunity to take another hard look at the old 3279, and bring it up to modern standards. Here's the result:
Without much doubt, this is the best this model has ever appeared. Details make the model, and the correct fuel tank, the angled 'rain gutter' on the roof, smaller decals on the frame and nose lettering, and additional weathering all combine to create a more plausible model.
This hobby will grow with you. There remains much to learn, of course; still, it is satisfying to see that, with some work, a model that stood out as being an early effort can be upgraded to fit better with the rest of the fleet.